Spring Boot自定义ID插入User报错：无法创建新行

我用Spring Boot搭建网页后端，集成Spring Security和OAuth2实现用户登录认证，登录时希望在后端存储用户基本信息（姓名、邮箱及OAuth生成的ID）。但调用user.save()方法时总是抛出错误，提示指定User不存在。

具体错误信息 #

org.springframework.dao.IncorrectUpdateSemanticsDataAccessException: Failed to update entity [User[id=google-1234, externalid=1234, externalidprovider=google, name=John Doe, email=john.doe@gmail]]; Id [google-1234] not found in database

我判断问题在于：明明要创建新用户，系统却尝试执行更新操作。我的id并非自动生成，而是用OAuth提供商的ID拼接而成（示例中的google-1234）。

相关代码细节 #

1. User实体定义（数据库为Postgres 16） #

@Table(name = "users")
public record User (
        @Id
        String id,
        String externalid,
        String externalidprovider,
        String name,
        @NotNull @Email
        String email
) {}

2. Controller代码 #

@RestController
@RequestMapping("/users")
public class UserController {
    private final UserRepository userRepository;

    public UserController(UserRepository userRepository) {
        this.userRepository = userRepository;
    }

    @ResponseStatus(HttpStatus.CREATED)
    @PostMapping("/upsert-google")
    User upsertGoogleUser(@AuthenticationPrincipal OAuth2User googlePrincipal) {
        logger.info("Upserting google user: {}", googlePrincipal);
        // Check if the user already exists
        if (googlePrincipal == null) {
            logger.error("Null OAuth2User principal provided");
            throw new IllegalArgumentException("Invalid Google user information");
        }

        String userId = "google-" + googlePrincipal.getAttribute("sub");
        logger.info("Upserting Google user with ID: {}", userId);

        // Check if the user already exists
        Optional<User> existingUserOpt = userRepository.findById(userId);

        if (existingUserOpt.isPresent()) {
            User existingUser = existingUserOpt.get();
            logger.info("Found existing user: {}", existingUser);
            return updatedUser;
        } else {
            User newUser = new User(
                userId,
                googlePrincipal.getAttribute("sub"),
                "google",
                googlePrincipal.getAttribute("name"),
                googlePrincipal.getAttribute("email")
            );
            logger.info("Creating new Google user: {}", newUser);
            return userRepository.save(newUser);
        }
    }
}

3. Repository代码 #

public interface UserRepository extends CrudRepository<User,String> {}

数据库初始化语句 #

DROP TABLE IF EXISTS Users CASCADE;
CREATE TABLE IF NOT EXISTS Users (
                                     id TEXT PRIMARY KEY,
                                     externalid TEXT,
                                     externalidprovider TEXT,
                                     name TEXT NOT NULL,
                                     email TEXT NOT NULL,
                                     membersince TIMESTAMP NOT NULL DEFAULT NOW(),
                                     lastlogin TIMESTAMP NOT NULL DEFAULT NOW()
);

目前我已手动编写了create方法并可正常使用，但无法使用Spring Data的基础INSERT操作，想确认是否存在配置错误。

内容的提问来源于stack exchange，提问作者Paco